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Mastering JavaScript Object-Oriented Programming

You're reading from   Mastering JavaScript Object-Oriented Programming Advanced patterns, faster techniques, higher quality code

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Product type Paperback
Published in Jun 2016
Publisher Packt
ISBN-13 9781785889103
Length 292 pages
Edition 1st Edition
Languages
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Toc

Table of Contents (13) Chapters Close

Preface 1. A Refresher of Objects FREE CHAPTER 2. Diving into OOP Principles 3. Working with Encapsulation and Information Hiding 4. Inheriting and Creating Mixins 5. Defining Contracts with Duck Typing 6. Advanced Object Creation 7. Presenting Data to the User 8. Data Binding 9. Asynchronous Programming and Promises 10. Organizing Code 11. SOLID Principles 12. Modern Application Architectures

Creating a singleton


Sometimes, we may need to have a single occurrence of an object throughout the application life. Consider, for example, a configuration manager or a cache manager. Since they provide a global point of access to an internal or external resource, they need to be implemented in a way so that only one instance must exist, that is, they need to be implemented as a singleton.

The singleton pattern is one of the simplest design patterns—it involves only one entity which is responsible for making sure it creates not more than one instance and provides a global point of access to itself. For a class-based language, this means that a class can be instantiated only one time and any attempt to create a new instance of the class returns the instance already created.

In JavaScript, we can create objects through the literal notation, so any such object is already a singleton:

var johnSingleton = { 
    name: "John", 
    surname: "Singleton" 
}; 

So, why do we need to implement this design...

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